圆红冬孢酵母类胡萝卜素代谢流的阻遏及走向

Inhibition and trend analysis of carotenoid metabolic flux of Rhodosporidium toruloides

以野生型的圆红冬孢酵母为出发菌株,利用常压室温等离子体(ARTP)进行诱变,筛选获得4株类胡萝卜素缺陷型圆红冬孢酵母突变株。对圆红冬孢酵母的野生型及类胡萝卜素缺陷型菌株进行发酵,并对其生物量、类胡萝卜素含量、油脂含量、脂肪酸组成及有机酸含量进行测定。结果表明,利用ARTP技术能够有效实现对类胡萝卜素代谢流的阻遏,突变株类胡萝卜素质量浓度较野生型菌株降低了70%。碳流代谢走向分析结果表明,类胡萝卜素代谢途径的阻断并未导致油脂合成途径的加强,反而造成圆红冬孢酵母生物量和油脂合成能力的分别下降48%和40%,对胞内脂肪酸组成也有较为显著的影响,其中突变株W-4所产硬脂酸、亚油酸及油酸质量分数较野生型菌株分别下降了60%、42%和77%。类胡萝卜素合成途径阻断后,碳流主要指向有机酸合成,其中乙醛酸、乳酸、苹果酸及琥珀酸变化较为显著。类胡萝卜素缺陷型突变株中大量积累的类胡萝卜素合成前体主要流入了有机酸合成途径中。

The wild type strain Rhodosporidium toruloides was used as original strain to conduct mutagenesis by atmospheric and room temperature plasma(ARTP). Four carotenoid-deficient R. toruloides mutants were obtained. The wild-type and mutant R. toruloides strains were fermented, of which the biomass, contents of carotenoid, lipid, fatty acid and organic acid were determined. The results showed that the defect of the carotenoid synthesis pathway could reduce the contents of carotenoid, biomass and lipid by 70%, 48% and 40%, respectively. The content of stearic acid, linoleic acid and oleic acid in carotenoid-deficient mutant W-4 decreased by 60%, 42% and 77%, respectively. The significant change in composition of intracellular fatty acids was also observed. The content of total organic acids in the supernatant of the mutants was significantly higher than that in the wild type, where the contents of glyoxylic acid, lactic acid, malic acid and succinic acid were clearly changed. The result suggested that precursor molecules that synthesized carotenoid have partially flowed into the organic acid synthesis pathway in carotenoid-deficient mutants.